DESCRIPTION (Adapted from applicant's description): The proposed study is designed to test the hypothesis that increasing the protein intake of very-low-birth-weight (VLBW) infants through protein supplementation of a preterm formula will lead to increased growth without adverse consequences. In a randomized double-blind study, three groups of 26 VLBW infants each (birth weight <1250g, gestational age <34 wks) will be enrolled when oral feedings reach 50 ml/kg/d and studied until a weight of 2000g is reached. The supplements will provide (1) an amount of a protein hydrolysate that will raise protein intake slightly above the estimated requirement; (2) half that amount of protein plus an equal amount of lactose; and (3) lactose only. The supplements will be equicaloric. They will be packaged by the pharmacy in color-coded capsules. The contents of the requisite number of capsules will be added to the daily supply of formula. As the infants' weight increases, the number of capsules will decrease from 4 capsules per 100 ml of formula for infants weighing <1000g to 2 capsules per 100 ml of formula for infants weighing 1500 - 2000g. Intakes of calories and of protein will be determined daily. The primary outcome will be growth, with measures of protein nutritional status and of erythropoietic activity as secondary outcomes.